Correction: Monaco et al. Chiral Phase Transfer Catalysis in the Asymmetric Synthesis of a 3,3-Disubstituted Isoindolinone and Determination of Its Absolute Configuration by VCD Spectroscopy. Molecules 2020, 25, 2272

In this note, we report a correction to the published article, Molecules2020, 25, 2272 [...].

In this note, we report a correction to the published article, Molecules 2020, 25, 2272; doi:10.3390/molecules25102272 [1], regarding the absolute configuration (AC) of the used catalyst IV in the preparation of the sample sent for a VCD analysis.
In the paper, the VCD analysis was performed on the sample (+)-1 to determine its absolute configuration and it was found that the AC is (R). This new compound was in fact synthetized with the catalyst (S,S)-IV (ent-IV in the article), while in the text it was erroneously reported that the used catalyst was IV with the (R,R) configuration.
Therefore, the reaction scheme should be corrected as follows: In this note, we report a correction to the published article, Molecules 2020, 25, 2272; doi:10.3390/molecules25102272, [1] regarding the absolute configuration (AC) of the used catalyst IV in the preparation of the sample sent for a VCD analysis.
In the paper, the VCD analysis was performed on the sample (+)-1 to determine its absolute configuration and it was found that the AC is (R). This new compound was in fact synthetized with the catalyst (S,S)-IV (ent-IV in the article), while in the text it was erroneously reported that the used catalyst was IV with the (R,R) configuration.
Therefore, the reaction scheme should be corrected as follows: Some other parts of the article must be corrected, as on page 4: Under the best conditions of entry 1 of Table 3, [1] the reaction was scaled up to 100 mg of 2-acetylbenzonitrile, using catalyst ent-IV (with S,S configuration), obtaining similar results in terms of yield and ee (90% and 50%, respectively). The enantiopurity of the product was further improved by means of a heterochiral crystallization process (1  Some other parts of the article must be corrected, as on page 4: Under the best conditions of entry 1 of Table 3, the reaction was scaled up to 100 mg of 2-acetylbenzonitrile, using catalyst ent-IV (with S,S configuration), obtaining similar results in terms of yield and ee (90% and 50%, respectively). The enantiopurity of the product was further improved by means of a heterochiral crystallization process (1 crystallizes as a racemate), leading to the isolation of 1 from the mother liquor in up to 96% ee and in an acceptable efficiency (45% yield), thus resulting in an overall process (asymmetric catalytic cyclization followed by crystallization) allowing for considerable quantities of almost enantiopure isoindolinone 1 from simple starting materials. This sample was used for the determination of the Absolute Configuration by VCD. In addition, the proposed reported mechanism of Scheme 2 [1] must be revised considering different interactions in the TS, as follows: crystallizes as a racemate), leading to the isolation of 1 from the mother liquor in up to 96% ee and in an acceptable efficiency (45% yield), thus resulting in an overall process (asymmetric catalytic cyclization followed by crystallization) allowing for considerable quantities of almost enantiopure isoindolinone 1 from simple starting materials. This sample was used for the determination of the Absolute Configuration by VCD.
In addition, the proposed reported mechanism of Scheme 2 [1] must be revised considering different interactions in the TS, as follows: The nature of this exact interaction mode remains speculative, but it is obvious that the bifunctional nature of the catalyst is crucial for obtaining the promising enantioselectivities achieved herein (the S,S-catalyst gives mainly the R product; the configuration is determined as described in the following chapter).
The experimental section, in particular: